Training for mapping swizzled data to command/address signals

ABSTRACT

Data pin mapping and delay training techniques. Valid values are detected on a command/address (CA) bus at a memory device. A first part of the pattern (high phase) is transmitted via a first subset of data pins on the memory device in response to detecting values on the CA bus; a second part of the pattern (low phase) is transmitted via a second subset of data pins on the memory device in response to detecting values on the CA bus. Signals are sampled at the memory controller from the data pins while the CA pattern is being transmitted to obtain a first memory device&#39;s sample (high phase) and the second memory device&#39;s sample (low phase) by analyzing the first and the second subset of sampled data pins. The analysis combined with the knowledge of the transmitted pattern on the CA bus leads to finding the unknown data pins mapping. Varying the transmitted CA patterns and the resulting feedbacks sampled on memory controller data signals allows CA/CTRL/CLK signals delay training with and without priory data pins mapping knowledge.

TECHNICAL FIELD

Embodiments of the invention relate to training of memory links. Moreparticularly embodiments of the invention relate to techniques forautomatically mapping swizzled data.

BACKGROUND

When memory training begins on a platform with poorly aligned Control,Clock and Command/Address (CA) signals, even the most basic commands,such as Reset or entry into CA Training mode, might not registercorrectly in some of the DRAM devices. Current solutions demand verystrict length matching and/or manual initial timing settings for allthese signal types for each problematic platform. As a result, much timeand efforts can be spent for just enabling the most basic trainingroutines to run.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and notby way of limitation, in the figures of the accompanying drawings inwhich like reference numerals refer to similar elements.

FIG. 1 is a timing diagram corresponding to one embodiment of a trainingtechnique for mapping of data lines.

FIG. 2 is one embodiment of a timing diagram for a training sequence.

FIG. 3 illustrates two training patterns that may be used.

FIG. 4 is a block diagram of one embodiment of an electronic system.

FIG. 5 is a flow diagram of one embodiment of a training sequence thatcan be utilized in the system of FIG. 4.

FIG. 6 is a flow diagram of one embodiment of a pre-training procedurefor CLK/CS/CA delays.

FIG. 7 is a flow diagram of one embodiment of a pre-training procedurefor CLK/CS/CA delays.

FIG. 8 is a flow diagram of one embodiment of data pin mapping that canbe used after pre-training.

FIG. 9 is a flow diagram of one embodiment data pin mapping that can beused without pre-training.

FIG. 10 is a flow diagram of one embodiment of a technique for CStraining that can be used after DQ mapping.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth.However, embodiments of the invention may be practiced without thesespecific details. In other instances, well-known circuits, structuresand techniques have not been shown in detail in order not to obscure theunderstanding of this description.

Low-Power DDR-3 (LPDDR-3) command/address (CA) training mode and moderegister readout (MRR) require specific data (DQ) pin mapping if thereis swapping on the board. Not allowing swapping on the board restrictsoptions to system designers and manufacturers by limiting productoptions and increasing design complexity. For example, mapping of all128 DQ pins for a typical two-channel LPDDR3 embodiment would requiresignificant human effort and may result in errors. It may also require acustom BIOS/MRC (Memory Reference Code) version for each board and foreach memory configuration option, resulting in complex productionenvironments and complex production management issues.

Techniques described herein can determine the mapping of requiredsignals automatically using memory device training modes. For example,the CA training mode for LPDDR3, and other similar training modes. Inone embodiment, the mapping technique uses a byte mapping (e.g., 8 bitsper 64-bit channel), which can eliminate monotonous manual labor and thecorresponding probability of errors, as well as allowing a universalBIOS version to work with many different boards/platforms without theneed to recompile the BIOS.

In one embodiment, when performing CA training, memory devices samplethe CA bus values and return feedback on the DQ pins. The memorycontroller and any training support mechanisms (e.g., software,firmware) can analyze the feedback and determine a next action. Due toan unknown DQ mapping, there is no immediate way for the memorycontroller to determine which input is routed to which memory data line.

FIG. 1 is a timing diagram corresponding to one embodiment of a trainingtechnique for mapping of data lines. In one embodiment, mapping of datapins is split in to even and odd training In other embodiments, othersplits or groupings can be used.

In one embodiment, clock signal 110 is used to drive transactions on theCA bus 120 and the data bus. In one embodiment, the CA High phase valuesmap to the even memory data outputs (e.g., DQ0, DQ2, DQ4) and the CA Lowphase values map to the odd memory data outputs (e.g., DQ1, DQ3, DQ5).

In one embodiment, transmitting a single CA phase with a value differentfrom all other CA pins and the second phase of the same pin will resultin a single data signal having a value different than the other pins(e.g., one of 16 pins are high). Cycling through the position of thesingle differing value allows the training mechanism to identify onedata pin at a time and generate an appropriate mapping in a moreefficient manner than possible using prior art techniques.

To achieve a faster mapping, for example, eight iterations rather than16 for 16 pins, a different CA phase per each four pins can be used. Forexample to find data pin 0 (DQ0) in Byte 0 and data pin 8 (DQ8) in Byte1, a value of “1” can be transmitted on CA0 and CA5 high phases, whileCA0 and CA5 low phases and all other CA pins transmit “0”. This resultsin a single “1” value on each DQ byte that provides feedback (lower twobytes of the memory device). The training mechanism then finds whichsingle DQ pin in each byte has the value of “1” and stores thatinformation for mapping and subsequent deswizzling.

In one embodiment, the following CA to DQ mapping may be utilized:

Clock CA0 CA1 CA2 CA3 CA5 CA6 CA7 CA8 Edge DQ0 DQ2 DQ4 DQ6 DQ8 DQ10 DQ12DQ14 Rising DQ1 DQ3 DQ5 DQ7 DQ9 DQ11 DQ13 DQ15 Falling

Previous DDR generations did not require signal mapping as describedabove. Common solutions for the LPDDR3 need for signal mapping included,for example, hardcoded tables with mapping data, which is an inefficientsolution for a large number of board variations and/or memoryconfigurations. Another existing (ineffective) solution is to disallowswapping DQ signals and bytes completely to avoid this—but it makesboard design very ineffective and complex.

In one embodiment, techniques described herein provide a trainingmechanism for concurrent initial pre-training of Control, Clock, Commandand Address signals timings for memory devices (e.g., LPDDR3). Thesemechanisms utilize a training mode, for example, the LPDDR3Command/Address (CA) Training mode, with unique training patterns thatdo not require prior Command/Address or Control signals training.

In one embodiment, while in CA Training mode, memory devices sample asingle transaction on CA bus and provide feedback on the DQ signals. TheCA0 . . . CA3 pins values on both High and Low phase map to DQ0 . . . 7outputs of each memory device (1st byte), while CA5 . . . 8 High and Lowphase values map to DQ8 . . . 15 outputs of each memory device (2ndbyte).

Because there is no complete DQ mapping at this point of training, apreselected pattern is transmitted on CA bus that does not rely onchecking the exact DQ feedback, but the sum of signals equal to “1” ineach data byte. In one embodiment, the pattern includes all the CA bustransitions to ensure coverage of both High and Low phase, while notproducing excessive stress by having only one level transition from 0 to1 or from 1 to 0) per signal during each iteration.

FIG. 2 is one embodiment of a timing diagram for a training sequence. Inone embodiment, on each of the CA pins (e.g., CA0 . . . 3 and CA5 . . .8), the following pattern is transmitted (or its opposite/inversedversion, as described below).

As a result, a different feedback will arrive on the DQ pins, dependingon Chip Select (Control) and CA relative timings versus the clock signalfor each memory device. If both CS 120 and CA 130 are aligned correctlywith respect to the clock signal, both clock phases will sample two CApins with value of “1” and another two with the value of “0,” resultingin four DQ pins with the value of “1.”

If either or both CA and CS buses are unaligned, incorrect valuesranging from two to six DQ pins sampled at “1” (exact values do notmatter). This allows the ability also distinguish the case of sample 0or 1 on all the DQ pins, meaning the memory device is not in CA Trainingmode.

If the DRAM device does not sample anything, it keeps the feedback onthe DQ pins constant, thus resulting in displaying an old, irrelevantfeedback to the memory controller. That is why we want to find out thisis the case. In one embodiment, in order to distinguish lack of sample(e.g., due to marginal/incorrect timing) from a correct timing, twounique inversed patterns can be used that both result in four “1”s ifsampled correctly, but with different signatures. Therefore, each validpoint should sample “4” with two different signatures. Any other resultis considered as failing point. FIG. 3 illustrates two training patternsthat may be used. Patterns of similar kind and similar characteristicswill achieve the same results.

In one embodiment specific to LPDDR-3 and related implementations,because the initial Clock/CTRL/CA timings might be invalid, there is noway to guarantee the initial Reset/Init and CA Training mode entrycommands are decoded correctly. In one embodiment, in order to guaranteethe Reset command success (e.g., MRW63 command), the CS can betransmitted signal for two consecutive cycles (“2N CS” mode).

At this point, all the MR values necessary are not yet available forLPDDR operation, but these values are not required yet. In oneembodiment, the only MRW needed is CA Training mode entry (e.g., MRW41),which might or might not succeed due to Clock/CTRL timing. Therefore,for the iterations that show incorrect results, if there indicationsthat the memory device is not in CA training mode, the CA Training modeis exited (in case some of DRAM devices on this rank are in it butothers not), reset the rank and enter the CA Training mode again.

Before any other memory device training steps can begin, the MRC mustmake sure the Control signals are aligned at all the memory (e.g., DRAM)devices, so all the issued commands register correctly. Because not allthese signals have matching lengths on some platforms due to designlimitations and/or errors, there is a need for mechanism to find theoptimal timings for these signals.

Described herein are techniques for training Control signals timingsthat are particularly useful for LPDDR3; however, other memory devicescan also be supported. In LPDDR3 embodiments, these techniques utilizethe LPDDR3 Command/Address (CA) Training mode and uses special trainingpatterns that do not require prior Command/Address signals training. Inother embodiments, similar training modes can be used similarly fortraining Control signal timing.

In one embodiment, The technique sweeps the Control delay across therange and for each value transmits both patterns (see FIG. 3) andcompares the read DQ results for each byte among themselves (should bedifferent for the two patterns) and the sum of values for each byte tofour.

After the test finishes, the middle point of the period that had validpoints is chosen and set to Control pins. In one embodiment, the test isrepeated for each channel and rank.

Current solutions rely on more precise signals length matching, whichcan be easier to achieve and/or less of an issue at slower speeds and onphysically larger system boards. If a mismatch occurred, manualadjustments are made to the timings for each case. This complicatesboards power-on activities and demands separate BIOS builds for eachsuch board.

Additionally, functional Control training steps are added per need,which run at much later MRC stage (after all the other signal timingsare already tuned). As a result, if the initial Control timing settingswere marginal, the systems become less stable and might not even reachthis advanced step without manual tuning of the initial timing settings.

FIG. 4 is a block diagram of one embodiment of an electronic system. Theelectronic system illustrated in FIG. 4 is intended to represent a rangeof electronic systems (either wired or wireless) including, for example,desktop computer systems, laptop computer systems, cellular telephones,personal digital assistants (PDAs) including cellular-enabled PDAs, settop boxes, tablets, etc. Alternative electronic systems may includemore, fewer and/or different components.

Electronic system 400 includes bus 405 or other communication device tocommunicate information, and processor 410 coupled to bus 405 that mayprocess information. While electronic system 400 is illustrated with asingle processor, electronic system 400 may include multiple processorsand/or co-processors. Electronic system 400 further may include randomaccess memory (RAM) or other dynamic storage device 420 (referred to asmain memory), coupled to bus 405 and may store information andinstructions that may be executed by processor 410. Main memory 420 mayalso be used to store temporary variables or other intermediateinformation during execution of instructions by processor 410.

Electronic system 400 may also include read only memory (ROM) and/orother static storage device 430 coupled to bus 405 that may store staticinformation and instructions for processor 410. Data storage device 440may be coupled to bus 405 to store information and instructions. Datastorage device 440 such as a magnetic disk or optical disc andcorresponding drive may be coupled to electronic system 400.

Electronic system 400 may also be coupled via bus 405 to display device450, such as a cathode ray tube (CRT) or liquid crystal display (LCD),to display information to a user. Alphanumeric input device 460,including alphanumeric and other keys, may be coupled to bus 405 tocommunicate information and command selections to processor 410. Anothertype of user input device is cursor control 470, such as a mouse, atrackball, or cursor direction keys to communicate direction informationand command selections to processor 410 and to control cursor movementon display 450.

Electronic system 400 further may include network interface(s) 480 toprovide access to a network, such as a local area network. Networkinterface(s) 480 may include, for example, a wireless network interfacehaving antenna 485, which may represent one or more antenna(e). Networkinterface(s) 480 may also include, for example, a wired networkinterface to communicate with remote devices via network cable 487,which may be, for example, an Ethernet cable, a coaxial cable, a fiberoptic cable, a serial cable, or a parallel cable.

In one embodiment, network interface(s) 480 may provide access to alocal area network, for example, by conforming to IEEE 802.11b and/orIEEE 802.11g standards, and/or the wireless network interface mayprovide access to a personal area network, for example, by conforming toBluetooth standards. Other wireless network interfaces and/or protocolscan also be supported.

IEEE 802.11b corresponds to IEEE Std. 802.11b-1999 entitled “Local andMetropolitan Area Networks, Part 11: Wireless LAN Medium Access Control(MAC) and Physical Layer (PHY) Specifications: Higher-Speed PhysicalLayer Extension in the 2.4 GHz Band,” approved Sep. 16, 1999 as well asrelated documents. IEEE 802.11g corresponds to IEEE Std. 802.11g-2003entitled “Local and Metropolitan Area Networks, Part 11: Wireless LANMedium Access Control (MAC) and Physical Layer (PHY) Specifications,Amendment 4: Further Higher Rate Extension in the 2.4 GHz Band,”approved Jun. 27, 2003 as well as related documents. Bluetooth protocolsare described in “Specification of the Bluetooth System: Core, Version1.1,” published Feb. 22, 2001 by the Bluetooth Special Interest Group,Inc. Associated as well as previous or subsequent versions of theBluetooth standard may also be supported.

In addition to, or instead of, communication via wireless LAN standards,network interface(s) 480 may provide wireless communications using, forexample, Time Division, Multiple Access (TDMA) protocols, Global Systemfor Mobile Communications (GSM) protocols, Code Division, MultipleAccess (CDMA) protocols, and/or any other type of wirelesscommunications protocol.

FIG. 5 is a flow diagram of one embodiment of a training sequence thatcan be utilized in the system of FIG. 4. The training sequence of FIG. 5provides a general overview of the training process.

Pre-training is performed for the CLK/CS/CA delays, 510. Embodiments forCLK/CS/CA pre-training are described in greater detail below. The data(DQ) pins are mapped, 520. Mapping of the DQ pins is performed asdescribed herein. CS vs. CLK training is performed, 530. CS vs. CLKtraining is performed as described above. CA vs. CLK training isperformed, 540. The CA vs. CLK training can be performed in any mannerknown in the art.

FIG. 6 is a flow diagram of one embodiment of a pre-training procedurefor CLK/CS/CA delays. FIG. 6 provides a simplified version of thepre-training procedure for CLK/CS/CA delays as compared to the versionof FIG. 7. The example of FIG. 6 relates to a LP-DDR configuration;however, the concepts described can be applicable to other DDRtechnologies and to non-DDR configurations as well. The host system isreset in 2N CS mode (e.g., MRW63 command), 605.

The system iterates on the CLK/CS/CA delays in rough steps, 610 toreduce run/boot time. If all of the delays are covered, 615, the systemcan operate to find optimal timing for the CLK/CS/CA signals, 620. Ifall of the delays are not covered, 615, the system enters CA training,625. In one embodiment, CA training is entered with the MRW41 commandand stretched CA; however, other techniques can be used for otherconfigurations (e.g., non-LPDDR3).

A first pattern (e.g., Pattern A, FIG. 3) is transmitted, 630. In oneembodiment, the sum of the data bits, per byte corresponding to thefirst is calculated and stored with a signature value for the firstpattern, 635. A second pattern (e.g., Pattern B, FIG. 3) is transmittedand the CA training mode is exited, 640. In one embodiment, the sum ofthe data bits, per byte corresponding to the second pattern iscalculated and stored with a signature value for the second pattern,645.

The pattern results are compared, 650, to determine whether the currenttiming parameters have passed, 655, or failed, 660. In one embodiment,the results comparison involves checking the number of ‘1’ bits receivedfor each training pattern. In one embodiment, if each pattern results infour ‘1’ bits received and the signatures for the two patterns aredifferent, the pattern training has passed.

FIG. 7 is a flow diagram of one embodiment of a pre-training procedurefor CLK/CS/CA delays. FIG. 7 provides a more complex version of thepre-training procedure for CLK/CS/CA delays as compared to the versionof FIG. 6. The example of FIG. 7 relates to a LP-DDR configuration;however, the concepts described can be applicable to other DDRtechnologies and to non-DDR configurations as well. The host system isreset in 2N CS mode (e.g., MRW63 command), 705.

The CA_ModeSucceeded flag is set to FALSE, 710. The system iterates onthe CLK/CS/CA delays in rough steps, 715. If all of the delays arecovered, 720, the system can operate to find optimal timing for theCLK/CS/CA signals, 725. If all of the delays are not covered, 720, ifthe CA_ModeSucceeded is still FALSE, the system enters CA training, 730.In one embodiment, CA training is entered with the MRW41 command andstretched CA; however, other techniques can be used for otherconfigurations (e.g., non-LPDDR3).

A first pattern (e.g., Pattern A, FIG. 3) is transmitted, 735. In oneembodiment, the sum of the data bits, per byte corresponding to thefirst is calculated and stored with a signature value for the firstpattern, 740. A second pattern (e.g., Pattern B, FIG. 3) is transmittedand the CA training mode is exited, 745. In one embodiment, the sum ofthe data bits, per byte corresponding to the second is calculated andstored with a signature value for the second pattern, 755.

The pattern results are compared, 760, to determine whether the currenttiming parameters have passed, 765, or failed, 770. In one embodiment,the results comparison involves checking the number of ‘1’ bits receivedfor each training pattern. In one embodiment, if each pattern results infour ‘1’ bits received and the signatures for the two patterns aredifferent, the pattern training has passed.

When the results indicate a pass, the CA_ModeSucceeded is marked TRUE,765. When the results indicate a fail, if the sum of bits for bothpatterns is greater than 0 and less than 8, 775, the CA_ModeSucceededflag is marked TRUE, 780. If the sum for both patterns is not greaterthan 0 and less than 8, CA training mode is exited (e.g., with MRW42command), 785.

The following flow description corresponds to one embodiment of atechnique for mapping data pins on a memory device.

-   -   1. Begin:    -   2. Reset memory device (e.g., MRW63) in 2N mode    -   3. Set CLK, CS, CA delay values (loop)        -   a. Enter CA Training mode (if needed)        -   b. Transmit pattern A        -   c. Store Result+signature        -   d. Option:            -   i. check for number of ‘1’-s                -   1. if 0 or 8                -    a. mark as failing point                -    b. exit CA training mode (e.g., MRW42)                -    c. jump to 3, update delay values and continue                    again through CA Training                -   2. if <4 or >4,                -    a. mark as failing point                -    b. jump to 3 but skip a.                -   3. if ==4—continue        -   e. Transmit pattern B        -   f. Check for number of ‘1’-s            -   i. if 0 or 8                -   1. mark as failing point                -   2. exit CA training mode (e.g., MRW42)                -   3. jump to 3, update delay values and continue again                    through CA Training            -   ii. if <4 or >4 or ==4 but signature is the same as for                A:                -   1. mark as failing point                -   2. jump to 3 (update delays) but skip a.            -   iii. if ==4 and signature is different from A's—mark as                passing point.        -   (After all the delay values are tried)    -   4. Decide on optimal delay point to be located in the middle of        the largest passing points region.

FIG. 8 is a flow diagram of one embodiment of data pin mapping that canbe used after pre-training described on FIGS. 6 and 7. In oneembodiment, a known bit pattern (e.g., one ‘1’ per byte) is iteratedthrough from memory (e.g., DRAM), 810. In one embodiment, the pattern isperformed for each byte in all bytes of a line in parallel.

If all of the data pins are covered, 820, mapping is complete. If all ofthe data pins are not covered, 820, then a CA pattern to produce asingle unique data pin level per byte it calculated and programmed, 830.The pattern is transmitted to memory, 840. In one embodiment, the DQpins are scanned to find the data pin that differs from the other datapins on a per-byte basis. Other sizes can also be supported. Thismapping is recorded for the processor (e.g., CPU) or other component tobe mapped to the data pin asserted above 850.

FIG. 9 is a flow diagram of one embodiment data pin mapping that can beused without pre-training described on FIGS. 6 and 7. The procedure ofFIG. 9 provides a technique to map data device pins (X1, X2, etc.) withprocessor pins (Y1, Y2, etc.), without the pre-training mechanismsdiscussed above.

In one embodiment, a pattern with one ‘1’ bit and seven ‘0’ bits isiterated on eight target CA pins mapped to 16 DQ pins for each twobytes, 910. Each CA pin is mapped to two data device pins (e.g., X1 andX2). If all CA pins are covered, 920, a CA pattern is programmed toproduce a ‘0’ on one CA phase (e.g., high) and a ‘1’ on the other CAphase (e.g., low) on all the CA pins concurrently, 930. In oneembodiment, for each DQ pin pair (e.g., X1 and X2) the DQ pin with the‘0’ is mapped to a first pin (e.g., X1) and the DQ pin with the ‘1’ ismapped to a second pin (e.g., X2), 940.

If all CA pins are not covered, 920, a CA pattern to produce a unique DClevel per CA pin is calculated and programmed, 950. This results in twoDQ pins with values that are different than the rest, which are X1 andX2. The pattern is transmitted, 960. The DQ pins that are different fromthe rest (Y1 and Y2) are found, 970. The mapping is recorded for theprocessor pin pair (Y1 and y2) for the corresponding data pin pair (X1and X2).

FIG. 10 is a flow diagram of one embodiment of a technique for CStraining that can be used after DQ mapping. In one embodiment, the CSvs. CLK delays are iterated, 1010. In one embodiment, the iterations arefor each rank. If all CS delays are covered, 1020, the optimal CS delaysetting is calculated, 1030.

If all CS delays are not covered, 1020, the first CS pattern istransmitted, 1040. The sum of the data bits for each byte of the firstpattern is stored with a signature for the first pattern, 1050. Thesecond CS pattern is transmitted, 1060. The sum of the data bits foreach byte of the second pattern is stored with a signature for thesecond pattern, 1070.

The pattern results are compared, 1080, to determine whether the currenttiming parameters have passed, 1090, or failed, 1095. In one embodiment,the results comparison involves checking the number of ‘1’ bits receivedfor each training pattern. In one embodiment, if each pattern results infour ‘1’ bits received (assuming the appropriate pattern from FIG. 3 orsimilar was used) and the signatures for the two patterns are different,the pattern training has passed.

In one embodiment, data line mapping is accomplished by detecting validvalues on a command/address (CA) bus at a memory device. A first patternis transmitted via a first subset of two or more data pins on the memorydevice corresponding to detecting the valid values on the CA bus.Signals are sampled from the data pins while the first pattern is beingtransmitted to obtain a first sample. A second pattern is transmittedvia a second subset of two or more data pins on the memory device.Signals are sampled from the data pins while the second pattern is beingtransmitted to obtain a second sample. The first sample and the secondsample are used to generate a data pin mapping.

In one embodiment, the memory device comprises a dynamic random accessmemory (DRAM). In one embodiment, the DRAM is a Low Power Double DataRate 3 (LPDDR3) compliant memory device. In one embodiment, the DRAM isa Double Data Rate (DDRx) compliant memory device. In one embodiment,the first subset comprises a first half of the data pins and the secondsubset comprises a second half of the data pins. In one embodiment, thefirst half comprises even numbered data pins and the second halfcomprises odd numbered data pins.

In one embodiment, a system includes at least one memory device havingcommand/address (CA) pins and data pins and a memory controller coupledwith at least one memory device via the CA pins and the data pins. Thememory controller to transmit valid values on a command/address (CA) busat a memory device, the memory device to transmit a first pattern via afirst subset of two or more data pins on the memory device, the memorycontroller to receive sampled signals from the data pins while the firstpattern is being transmitted to obtain a first sample, transmit a secondpattern via a second subset of two or more data pins on the memorydevice, receive sampled signals from the data pins while the secondpattern is being transmitted to obtain a second sample, and use thefirst sample and the second sample to generate a data pin mapping.

In one embodiment, the memory controller transmits a (single) pattern onCA pins and the memory device samples each CA pin twice and returns theresult on even and odd data pins accordingly. The memory device does notreceive anything on the data bus in this case, though, only the memorycontroller does.

In one embodiment, the memory device comprises a dynamic random accessmemory (DRAM). In one embodiment, the DRAM is a Low Power Double DataRate 3 (LPDDR3) compliant memory device. In one embodiment, the DRAM isa Double Data Rate (DDRx) compliant memory device. In one embodiment,the first subset comprises a first half of the data pins and the secondsubset comprises a second half of the data pins. In one embodiment, thefirst half comprises even numbered data pins and the second halfcomprises odd numbered data pins.

In one embodiment, a system includes a memory controller and a memorydevice having command/address (CA) pins and data pins. The memory devicecoupled to communicate with the memory controller via the CA pins andthe data pins, the memory device to detect valid values on acommand/address (CA) bus at a memory device, receive a first pattern viaa first subset of two or more data pins on the memory device, samplesignals from the data pins while the first pattern is being transmittedto obtain a first sample in response to detecting the valid values onthe CA bus, receive a second pattern via a second subset of two or moredata pins on the memory device, sample signals from the data pins whilethe second pattern is being transmitted to obtain a second sample, sendthe first sample and the second sample to the memory controller. Thememory controller generates a data pin mapping based on the first sampleand the second sample.

In one embodiment, the memory device comprises a dynamic random accessmemory (DRAM). In one embodiment, the DRAM is a Low Power Double DataRate 3 (LPDDR3) compliant memory device. In one embodiment, the DRAM isa Double Data Rate (DDRx) compliant memory device. In one embodiment,the first subset comprises a first half of the data pins and the secondsubset comprises a second half of the data pins. In one embodiment, thefirst half comprises even numbered data pins and the second halfcomprises odd numbered data pins.

A memory device includes command/address (CA) pins, data pins andcontrol logic coupled with the CA pins and the data pins. The controllogic to detect valid values on a command/address (CA) bus at a memorydevice, receive a first pattern via a first subset of two or more datapins on the memory device, sample signals from the data pins while thefirst pattern is being transmitted to obtain a first sample in responseto detecting the valid values on the CA bus, receive a second patternvia a second subset of two or more data pins on the memory device,sample signals from the data pins while the second pattern is beingtransmitted to obtain a second sample, send the first sample and thesecond sample to the memory controller.

In one embodiment, the memory device comprises a dynamic random accessmemory (DRAM). In one embodiment, the DRAM is a Low Power Double DataRate 3 (LPDDR3) compliant memory device. In one embodiment, the DRAM isa Double Data Rate (DDRx) compliant memory device. In one embodiment,the first subset comprises a first half of the data pins and the secondsubset comprises a second half of the data pins. In one embodiment, thefirst half comprises even numbered data pins and the second halfcomprises odd numbered data pins.

In one embodiment, a memory controller includes command/address (CA)pins, data pins and control logic coupled with the CA pins and the datapins. The memory controller to communicate with at least one memorydevice via the CA pins and the data pins, the memory controller totransmit valid values on a command/address (CA) bus at a memory device,receive sampled signals from the data pins while the first pattern isbeing transmitted to obtain a first sample, transmit a second patternvia a second subset of two or more data pins on the memory device,receive sampled signals from the data pins while the second pattern isbeing transmitted to obtain a second sample, and use the first sampleand the second sample to generate a data pin mapping.

In one embodiment, the memory device comprises a dynamic random accessmemory (DRAM). In one embodiment, the DRAM is a Low Power Double DataRate 3 (LPDDR3) compliant memory device. In one embodiment, the DRAM isa Double Data Rate (DDRx) compliant memory device. In one embodiment,the first subset comprises a first half of the data pins and the secondsubset comprises a second half of the data pins. In one embodiment, thefirst half comprises even numbered data pins and the second halfcomprises odd numbered data pins.

Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the invention. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment.

While the invention has been described in terms of several embodiments,those skilled in the art will recognize that the invention is notlimited to the embodiments described, but can be practiced withmodification and alteration within the spirit and scope of the appendedclaims. The description is thus to be regarded as illustrative insteadof limiting.

What is claimed is:
 1. A method comprising: detecting valid values on acommand/address (CA) bus at a memory device; transmitting, with a memorycontroller, a first pattern on the CA bus resulting in DRAM transmittinga first set of values on the Data pins producing a unique sum of ‘1’-sper byte. sampling signals from the data pins after the first pattern isbeing transmitted to obtain a first sample; transmitting, with thememory controller, a second pattern on the CA bus resulting in DRAMtransmitting a second set of values on the Data pins producing a uniquesum of ‘1’-s per byte sampling signals from the data pins after thesecond pattern is being transmitted to obtain a second sample; using thefirst sample and the second sample to generate a data pin mapping. 2.The method of claim 1 further comprising using the first sample and thesecond sample to achieve CLK/CS/CA rough resolution pre-training and CSfine resolution training.
 3. The method of claim 1 wherein the memorydevice comprises a dynamic random access memory (DRAM).
 4. The method ofclaim 3 wherein the DRAM is a Low Power Double Data Rate 3 (LPDDR3)compliant memory device.
 5. The method of claim 3 wherein the DRAM is aDouble Data Rate (DDRx) compliant memory device.
 6. The method of claim1 wherein the first subset comprises a first half of the data pins andthe second subset comprises a second half of the data pins.
 7. Themethod of claim 6 wherein the first half comprises even numbered datapins and the second half comprises odd numbered data pins.
 8. A systemcomprising: at least one memory device having command/address (CA) pinsand data pins; a memory controller coupled with the at least one memorydevice via the CA pins and the data pins, the memory controller totransmit valid values on a command/address (CA) bus at a memory device,transmit a first pattern on the CA bus, receive sampled signals from thedata pins after the first pattern is being transmitted to obtain a firstsample, transmit a second pattern on the CA bus, receive sampled signalsfrom the data pins while the second pattern is being transmitted toobtain a second sample, and use the first sample and the second sampleto generate a data pin mapping.
 9. The system of claim 8 wherein thememory device comprises a dynamic random access memory (DRAM).
 10. Thesystem of claim 9 wherein the DRAM is a Low Power Double Data Rate 3(LPDDR3) compliant memory device.
 11. The system of claim 9 wherein theDRAM is a Double Data Rate (DDRx) compliant memory device.
 12. A systemcomprising: a memory controller; a memory device having command/address(CA) pins and data pins, the memory device coupled to communicate withthe memory controller via the CA pins and the data pins, the memorydevice to detect valid values on a command/address (CA) bus at a memorydevice, receive a first pattern via a first subset of two or more datapins on the memory device, sample signals from the data pins while thefirst pattern is being transmitted to obtain a first sample in responseto detecting the valid values on the CA bus, receive a second patternvia a second subset of two or more data pins on the memory device,sample signals from the data pins while the second pattern is beingtransmitted to obtain a second sample, send the first sample and thesecond sample to the memory controller; wherein the memory controllergenerates a data pin mapping based on the first sample and the secondsample.
 13. The system of claim 12 wherein the memory device comprises adynamic random access memory (DRAM).
 14. The system of claim 12 whereinthe DRAM is a Low Power Double Data Rate 3 (LPDDR3) compliant memorydevice.
 15. The system of claim 12 wherein the DRAM is a Double DataRate (DDRx) compliant memory device.
 16. The system of claim 12 whereinthe first subset comprises a first half of the data pins and the secondsubset comprises a second half of the data pins.
 17. The system of claim12 wherein the first half comprises even numbered data pins and thesecond half comprises odd numbered data pins.
 18. A memory controllercomprising: command/address (CA) pins; data pins; and control logiccoupled with the CA pins and the data pins, the memory controller tocommunicate with the at least one memory device via the CA pins and thedata pins, the memory controller to transmit valid values on acommand/address (CA) bus at a memory device, transmit a first patternvia a first subset of two or more data pins on the memory device,receive sampled signals from the data pins while the first pattern isbeing transmitted to obtain a first sample, transmit a second patternvia a second subset of two or more data pins on the memory device,receive sampled signals from the data pins while the second pattern isbeing transmitted to obtain a second sample, and use the first sampleand the second sample to generate a data pin mapping.
 19. The memorycontroller of claim 18 wherein the memory device comprises a dynamicrandom access memory (DRAM).
 20. The memory controller of claim 18wherein the DRAM is a Low Power Double Data Rate 3 (LPDDR3) compliantmemory device.
 21. The memory controller of claim 18 wherein the DRAM isa Double Data Rate (DDRx) compliant memory device.